THE NEUROSTEROID 3-ALPHA-HYDROXY-5-ALPHA-PREGNAN-20-ONE INDUCES CATALEPSY IN MICE

Intracerebroventricular injection of the neurosteroid 3 alpha-hydroxy- 5 alpha-pregnan-20-one (3 alpha,5 alpha THP) induced catalepsy in mice , within less than 10 min of its administration, which lasted for more than 3 h. This catalepsy was reversed by i.p. administration of picro toxin, bicuculline, bromocriptine and levodapa-plus-carbidopa combinat ion. A low i.p. dose of 3 alpha,5 alpha THP (1.5 mg/kg) did not induce catalepsy. However, significant catalepsy was noted when 3 alpha,5 al pha THP (1.5 mg/kg) was administered by the i.p. route in the mice pre treated with subcataleptic doses of haloperidol, muscimol or aminooxya cetic acid, The results, for the first time, demonstrate the catalepto genic potential of 3 alpha,5 alpha THP and suggest that neurosteroids may affect central dopaminergic transmission through their direct acti on on GABA(A) receptors. (C) 1998 Elsevier Science Ireland Ltd. All ri ghts reserved.